BS AU 138b:2000

This British Standard specifies the dimensions required for correct mating of “contact” type couplings for connecting the pneumatic braking system of towing vehicles to trailers or semi-trailers. If not specifically dimensioned, the couplings may follow a form to suit the manufacturer. This British Standard also specifies performance requirements for the couplings, identity markings, serviceability, inspections, and maintenance.

The layout and position of the couplings on the vehicle are defined in BS AU 195a:1991 and are not incorporated in this revised British Standard.

Rubber hose assemblies are specified in BS AU 110a:1995 and are not incorporated in this revised British Standard.

Coiled pipe assemblies are specified in ISO 7375-1:1996, ISO 7375-2:1998, ISO 7628-1:1998, and ISO 7628-2:1998, and are not incorporated in this revised British Standard.

This British Standard applies to two-line pneumatic braking systems and to three line pneumatic braking systems that include a secondary line.

This British Standard specifies C type and CA type “contact” couplings. C type couplings are used in two line braking systems, and the CA type exclusively for the secondary line of a three line braking system. Each of the assemblies specified in this British Standard are intentionally physically non-interchangeable. It is further intended that each of the assemblies cannot be dismantled or repaired. This British Standard specifies the following:

1. the form and dimensions of the mating parts of the C type “contact” coupling and for the self-sealing valve and valve lifter to be incorporated in the coupling, to enable it to be used on the control or on the supply line of a two-line or three-line pneumatic braking system;
2. the form and dimensions of the mating parts of the CA type “contact” coupling and for the self-sealing valve incorporated into the female coupling, to enable it to be used on the secondary line of a three-line pneumatic braking system.